1. FIELD OF THE INVENTION
The present invention relates to a plate filter for filtering liquids, especially wine, beer, or liquid chemicals, including a tank in which plate-like filter elements are disposed one above the other, a hollow shaft that extends through the center of the filter elements, and at least one vertical feed line from which feed channels branch off to the filter elements.
2. DESCRIPTION OF THE PRIOR ART
With known plate filters of this general type, a plurality of filter elements are provided that are disposed one above the other on a central shaft. This shaft can be driven by means of a motor in order to cleanse the filter elements. The liquid that is to be filtered (the so-called unfiltered material) passes from the outside, i.e. from the periphery of each filter element, inwardly toward the center of the filter elements, where the cleansed liquid is withdrawn by appropriate outlets. With these heretofore known plate filters, there is the drawback that the feed of the unfiltered material from the outside of the filter elements inwardly does not take place uniformly, so that material does not flow uniformly to the individual filter elements in the desired manner. A particular drawback is that the filter aid, for example diatomite, that is mixed with the unfiltered material, is predominantly deposited on the periphery, i.e. in the outer zones, of the individual filter elements as the material flows from the outside into the individual filter elements due to the sedimentary property of this additive. As a result, a nonuniform coating of the individual filter elements takes place in such a way that more filtrate is deposited in the outer zones than in the inner zones.
Furthermore, due to nonuniform inward flow of the unfiltered material from the outside, nonuniform depositing or even partial separating or rinsing of the filter mass itself can occur, as a result of which a uniformity of the filtering process per unit of surface area/filter surface is not assured, which can have a disadvantageous effect upon the useful life of the filter and the quality of the filtering process. The nonuniform deposition of the expensive filter aid additionally leads to a very incomplete utilization of the filter aid, so that the filtering process as a whole has an unfavorable effectiveness.
It is an object of the present invention to further improve a plate filter of the aforementioned general type in such a way that each individual filter element is substantially uniformly supplied with the liquid that is to be filtered, and a better utilization of the filter aid, as well as a higher filtration effectiveness, is achieved.